From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06646C7EE22 for ; Wed, 10 May 2023 17:25:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236555AbjEJRZm (ORCPT ); Wed, 10 May 2023 13:25:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235609AbjEJRZj (ORCPT ); Wed, 10 May 2023 13:25:39 -0400 Received: from fgw21-7.mail.saunalahti.fi (fgw21-7.mail.saunalahti.fi [62.142.5.82]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA5AA5595 for ; Wed, 10 May 2023 10:25:34 -0700 (PDT) Received: from localhost (88-113-26-95.elisa-laajakaista.fi [88.113.26.95]) by fgw21.mail.saunalahti.fi (Halon) with ESMTP id aa706346-ef57-11ed-abf4-005056bdd08f; Wed, 10 May 2023 20:25:32 +0300 (EEST) From: andy.shevchenko@gmail.com Date: Wed, 10 May 2023 20:25:31 +0300 To: Jean-Michel Hautbois Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, brgl@bgdev.pl, linus.walleij@linaro.org Subject: Re: pca953x issue when driving a DSI bridge Message-ID: References: <0b3a257a-f1e5-ad86-4c69-93e038a33ce9@yoseli.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0b3a257a-f1e5-ad86-4c69-93e038a33ce9@yoseli.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wed, May 10, 2023 at 06:12:19PM +0200, Jean-Michel Hautbois kirjoitti: > Hello there ! > > I have a custom board, based on a i.MX8mm SoC which has a MIPI-DSI to eDP > bridge (namely, a TI sn65dsi86). This bridge has a DSI enable pin, which is > basically its reset pin, connected to my PCA9539 GPIO expander. > > The issue is that this pin can't be sleeping, and it is tested in the > gpiod_set_value() function. > > Here is where it fails in my dmesg: ... > [ 11.273968] gpiod_set_value+0x5c/0xcc > [ 11.277722] ti_sn65dsi86_resume+0x4c/0x94 [ti_sn65dsi86] Your problem even worse, i.e. ->resume() might sleep. > [ 11.283131] __rpm_callback+0x48/0x19c > [ 11.286885] rpm_callback+0x6c/0x80 > [ 11.290375] rpm_resume+0x3b0/0x660 > [ 11.293864] __pm_runtime_resume+0x4c/0x90 > [ 11.297960] __device_attach+0x90/0x1e4 > [ 11.301797] device_initial_probe+0x14/0x20 > [ 11.305980] bus_probe_device+0x9c/0xa4 > [ 11.309817] device_add+0x3d8/0x820 > [ 11.313308] __auxiliary_device_add+0x40/0xa0 > [ 11.317668] ti_sn65dsi86_add_aux_device.isra.0+0xb0/0xe0 [ti_sn65dsi86] > [ 11.324381] ti_sn65dsi86_probe+0x20c/0x2ec [ti_sn65dsi86] > [ 11.329876] i2c_device_probe+0x3b8/0x3f0 > [ 11.333889] really_probe+0xc0/0x3dc ... > I suppose this is not a corner case and we may have other drivers and other > boards connecting a GPIO which can sleep in a context where it should not ? > > I would like to add one thing: on this board, the expander is routed in a > way that makes it impossible to "sleep" as the reset is forced pulled-up and > the power regulators are fixed and can't be stopped. Can you elaborate why you think there is a problem? > I don't know how to address this issue nicely and any thoughts is > appreciated ! As a workaround you can consider the code around i2c_in_atomic_xfer_mode() but since I have heard about i.MX8 so many negative remarks which makes me think that hardware is a train wreck and shouldn't be used at all. -- With Best Regards, Andy Shevchenko